1. Field of the Invention
The present invention relates to a golf club head of a metal shell structure and a golf club equipped with the golf club head.
2. Description of Related Art
The so-called wood-type golf club head having a wider sweet spot and capable of obtaining a straight and longer drive without causing a slice or a hook has been desired.
To cope with this request, the present applicant proposed a golf club head of a metal shell structure through Japanese Patent No. 2831585. This golf club head is provided with a recess formed at a widthwise-central portion of the sole and extending backward from a position apart from the face. The recess is opened at the back face.
The present invention is directed to an improvement of the aforementioned golf club head.
It is an object of the present invention to provide a golf club head and a golf club equipped with the golf club head with a larger sweet spot and a lower center of gravity, which enables a straight and longer drive.
It is another object of the present invention to provide a golf club head and a golf club equipped with the golf club head capable of reducing friction between the golf club head and a ground and guiding the golf cub head straight along the direction of hitting a ball even in cases where the sole of the golf club head comes into contact with the ground during the swing.
According to the first aspect of the present invention, a golf club head of a metal shell structure includes a sole face gently downwardly curved from a heel portion toward a toe portion, a generally rectangular protrusion having a predetermined width, the protrusion being downwardly protruded from an intermediate region of the sole face between the heel portion and the toe portion and extending backward from a face, and a recess formed at a widthwise-central portion of the protrusion and extending backward straightly with a predetermined width from a position apart from the face by a predetermined distance, thereby forming a pair of parallel rail portions at both sides of the recess, the recess being opened at a back face.
According to this structure, the depth of the center of gravity of the golf club head increases because of the weight of the side walls constituting the recess, resulting in an enlarged sweet spot. Accordingly, the hit probability within the sweet spot can be increased, which in turn enables an intended straight driving. Furthermore, the protrusion formed on the sole surface lowers the center of gravity, resulting in a higher ballistic course and an increased carry. Furthermore, since a pair of parallel rail portions are formed at both sides of the recess, the friction between the golf club head and a ground can be reduced and the golf club head can be guided straight along the direction of hitting a ball even in cases where the sole of the golf club head comes into contact with the ground during the swing.
It is preferable that each of the rail portions is provided with a straight guide groove at a widthwise-central portion thereof. This straight guide groove further enhances the aforementioned straight driving, which further stabilizes a swing.
It is preferable that the protrusion is formed at a region having a width of about xc2xd to about xc2xc of a length from the heel portion to the toe portion.
It is preferable that a face-side tip portion of the recess is formed into a semicircular shape.
It is preferable that the recess includes a front straight portion having a generally constant width and a rear opening portion continued from the front straight portion and that the rear opening portion gradually increases in width toward a back face and has a rear end opened at the back face.
It is preferable that the front straight portion has a length falling within the range of from 10 to 40 mm, more preferably from 20 mm to 35 mm, a width falling within the range of from 8 to 20 mm, more preferably from 10 to 15 mm, and a depth falling within the range of from 3 mm to xc2xd of a head height, more preferably 5 mm to 15 mm.
According to the another aspect of the present invention, a golf club is provided with a golf club head of a metal shell structure which includes a sole face gently downwardly curved from a heel portion toward a toe portion, a generally rectangular protrusion having a predetermined width, the protrusion being downwardly protruded from an intermediate region of the sole face between the heel portion and the toe portion and extending backward from a face, and a recess formed at a widthwise-central portion of the protrusion and extending backward straightly with a predetermined width from a position apart from the face by a predetermined distance, thereby forming a pair of parallel rail portions at both sides of the recess, the recess being opened at a back face.